JP5762022B2 - Pressure roller and fixing device equipped with the pressure roller - Google Patents

Description

  The present invention relates to a pressure roller suitable for use in a fixing device mounted on an image forming apparatus such as an electrophotographic copying machine or an electrophotographic printer, and a fixing device having the pressure roller.

As a fixing device mounted on an electrophotographic printer or copying machine, a heat having a halogen heater, a fixing roller heated by the halogen heater, and a pressure roller that forms a nip portion in contact with the fixing roller There is a roller type.
Further, as a fixing device, a heater having a heating resistor on a ceramic substrate, a fixing film that moves while contacting the heater, a pressure roller that forms a nip portion with the heater via the fixing film, There is a film heating system having
Each of the fixing devices of the heat roller system or the film heating system fixes the toner image on the recording material while nipping and conveying the recording material carrying the unfixed toner image at the nip portion.
In general, a release layer is provided on the surface layer of the fixing roller, fixing film, and pressure roller used in these systems in order to prevent adhesion of toner, and a fluororesin is preferably used.
However, since the fluororesin is a highly insulating material, it is easily charged and does not easily escape static electricity. For this reason, when the recording material carrying the unfixed toner image is conveyed to the nip portion of the fixing device, the unfixed toner is electrically attached to the surface of the fixing roller or the fixing film and is recorded when the fixing roller or the fixing film is circulated. A so-called electrostatic offset image (hereinafter referred to as an electrostatic offset) that is fixed to the material may be generated.
Therefore, a proposal in which a charge control agent is dispersed in a fluororesin so that the fluororesin in the release layer is not charged, a proposal to reduce the resistance of a part or a plurality of layers of the pressure roller, a fixing roller or a fixing belt A proposal has been made that an antistatic agent is contained in the rubber layer.

For example, in Patent Document 1, a fixing device including a fixing member having a heating element therein and a pressure roller rotatably disposed opposite to the fixing member, the pressure roller includes a conductive member. There has been proposed a fixing device having an elastic layer on a core metal and a surface layer of a conductive PFA tube formed on the elastic layer.
Patent Document 2 discloses a pressure roller having a structure in which a release layer, an adhesive layer, an elastic layer, and a core metal are formed in order from the surface of the pressure roller, the release layer is insulative, and the adhesive layer is conductive. Carbon black has been proposed as a particle to be dispersed in the adhesive layer.
Patent Document 3 discloses that an organopolysiloxane containing 100 parts by mass of an alkenyl group bonded to at least two silicon atoms in one molecule and an effective amount of a curing agent for curing the organopolysiloxane are charged. An insulating silicone rubber composition for a fixing roller or fixing belt containing 0.001 to 2 parts by mass of an inhibitor has been proposed, and its application to a rubber elastic layer is disclosed.

Japanese Patent Laid-Open No. 04-019687 JP 2002-258649 A JP 2006-265340 A

However, the conventional configuration has the following problems regarding electrostatic offset and pressure roller contamination.
The electrostatic offset is generated when an electric field that attracts toner from the recording material to the surface of the fixing film or the fixing roller is formed when the surface potential of the pressure roller is excessively increased by frictional charging. Occurs continuously. On the other hand, the toner contamination is that the offset toner adheres and accumulates on the surface layer of the pressure roller, and the toner adheres as a lump to the back surface of the recording material at a certain timing, resulting in an image defect.

Here, in the case of the conventional example in which the conductive PFA tube is provided on the pressure roller surface layer, the toner contamination of the pressure roller is likely to occur. In this conductive PFA tube, carbon is added to the insulating PFA in order to provide conductivity, and the electrostatic offset is superior to the insulating PFA tube not containing the conductive material, but the toner releasability is inferior. ing.
In addition, although the releasability is improved by reducing the amount of carbon added, the electrostatic offset worsens conversely, so there is a trade-off between electrostatic offset and pressure roller contamination for conductive PFA tubes with carbon addition. Are in a relationship.
In addition, the pressure roller with a configuration in which the release layer of the pressure roller is composed only of an insulating fluororesin tube and the electroconductive particles such as carbon black are dispersed in the adhesive layer between the release layer and the elastic layer is fixed. Depending on the configuration of the device, the electrostatic offset suppression capability may be low.
Accordingly, an object of the present invention is to provide a pressure roller and a fixing device that can stably suppress electrostatic offset without causing toner contamination on the pressure roller.

The present invention for solving the above-mentioned problems is a pressure roller that forms a nip portion for heating while nipping and conveying a recording material carrying an image together with a heating member, and includes at least a core metal and an elastic layer When, a release layer, the pressure roller having a bonding layer for bonding the release layer and the elastic layer, wherein the adhesive layer contains a monomer electrolyte, the monomer electrolyte fluorosurfactant It is characterized by being.
The present invention also provides a pressure roller for forming a nip portion for heating while sandwiching and transporting a recording material carrying an image together with a heating member, comprising at least a core metal, an elastic layer, a release layer, And a pressure roller having an adhesive layer for bonding the elastic layer and the release layer, wherein the adhesive layer is formed of silicone rubber having an adhesive component and contains a monomer electrolyte. And

  According to the present invention, the surface of the pressure roller is not excessively charged, and both suppression of electrostatic offset and prevention of contamination of the pressure roller can be achieved.

Schematic configuration diagram of fixing device Explanatory drawing of Example 11.

(1) Fixing device 6
An image forming apparatus equipped with a fixing device is a well-known configuration and will not be described. FIG. 1 is a schematic configuration model diagram of the fixing device 6 used in this example. Reference numeral 21 denotes a substantially semicircular arc-shaped cross section, and a horizontally long film guide member (stay) whose longitudinal direction is the longitudinal direction in the drawing, and 22 is formed along the longitudinal direction at a substantially central portion of the lower surface of the film guide member 21. A horizontally long heater 23 accommodated and held in the groove is an endless belt-like heat-resistant belt (fixing film) that is loosely fitted on the film guide member 21 with the heater. These 21-23 comprise the heating member of a present Example. A pressure roller 24 is pressed against the lower surface of the heater 22 with the belt 23 interposed therebetween.

N is a fixing nip portion formed by the heater 22 and the pressure roller 24 with the heat-resistant belt 23 interposed therebetween. The pressure roller 24 is rotationally driven by a drive source M. The film guide member 21 is, for example, a molded product of a heat resistant resin such as PPS (polyphenylene sulfite) or a liquid crystal polymer.
The heater 22 is a horizontally long and thin heater substrate 22a made of alumina, AlN, or the like, and has a resistance heating such as a linear or narrow strip Ag / Pd formed on the surface side (film sliding surface side) along the length. This is a ceramic heater with a low heat capacity as a whole, comprising the body 22b, a thin surface protective layer 22c such as a glass layer, and a temperature detection element 22d such as a thermistor disposed on the back side of the heater substrate 22a. The ceramic heater 22 is controlled to maintain a predetermined fixing temperature (control target temperature) by a power control unit including a temperature detection element 22d after the temperature is rapidly raised by supplying power to the heating element 22b.
The heat-resistant belt 23 is a composite layer film having a total thickness of 400 μm or less, preferably 50 μm or more and 300 μm or less in order to reduce the heat capacity and improve the quick start performance of the apparatus.
The base layer of the heat-resistant belt 23 is formed of a heat-resistant resin such as polyimide, polyamideimide, or PEEK, or a metal member such as SUS, Al, Ni, Ti, or Zn having heat resistance and high thermal conductivity, alone or in combination. It is. An elastic layer for improving toner fixing performance may be formed on the base layer, and silicone rubber, fluororubber, etc. to which a heat conductive filler, a reinforcing material and the like are added are preferably used.
The main polymer of the heat-resistant belt release layer is composed of a fluororesin, and specific examples are listed as follows. Homopolymers such as polyvinylidene fluoride and polyvinyl fluoride, binary copolymers of ethylene and tetrafluoroethylene (hereinafter abbreviated as ETFE), binary copolymers of ethylene and trifluoroethylene chloride, And a binary copolymer of ethylene fluoride and perfluoroalkyl vinyl ether (hereinafter abbreviated as PFA), and a binary copolymer of tetrafluoroethylene and hexafluoropolypropylene. Of these, PFA and ETFE are more preferable from the viewpoints of moldability, heat resistance, and bending resistance. Each can be used alone or in combination of two or more. If necessary, the release layer may contain a conductive member such as carbon black or an ion conductive substance.

The pressure roller 24 includes a cored bar 24a made of iron or aluminum, a material described in detail in the next item (2), a rubber elastic layer 24c obtained by a manufacturing method, adhesive layers 24b and 24d, a release layer. 24e and the like.
A voltage application circuit 25 for electrically holding the toner on the recording material P on the recording material at the fixing nip portion N is electrically connected to the core metal 24 a of the pressure roller 24. The voltage application circuit 25 may be connected from the elastic layer 24c or the adhesive layers 24b and 24d. The voltage application circuit may be connected to a pressure roller or a heating member. Further, the voltage application circuit may be separately connected to the pressure roller and the heating member.
The heat-resistant belt 23 is driven by the rotation of the pressure roller 24 when the pressure roller 24 is driven to rotate counterclockwise as indicated by the arrow b at least when image formation is performed. That is, when the pressure roller 24 is driven, a rotational force acts on the heat resistant belt 23 by the frictional force between the pressure roller 24 and the outer surface of the heat resistant belt 23 in the fixing nip portion N. When the heat-resistant belt rotates, the inner surface of the heat-resistant belt slides in close contact with the lower surface that is the surface of the heater 22 in the fixing nip N. In this case, in order to reduce the sliding resistance between the inner surface of the heat resistant belt 23 and the lower surface of the heater 22 on which it slides, a lubricant such as heat resistant grease may be interposed therebetween.
When the recording material P is nipped and conveyed at the fixing nip portion N, the toner image carried on the recording material P is heated and fixed. The recording material P that has passed through the fixing nip N is separated from the outer surface of the heat resistant belt 23 and conveyed.
In the film heating type fixing device 6 as in this example, the heater 22 having a small heat capacity and a fast temperature rise can be used, and the time until the heater 22 reaches a predetermined temperature can be greatly shortened. Since it can be easily raised to a high temperature even from room temperature, it is not necessary to adjust the standby temperature when the apparatus is in a standby state during non-printing, and power can be saved. Further, the rotating heat-resistant belt 23 is not substantially tensioned except for the fixing nip portion N, and a flange member that simply receives the end of the heat-resistant belt 23 as a belt displacement movement restricting means. Only.

(2) Pressure roller 24
The material constituting the pressure roller 24 as a pressure member in the fixing device 6 and the molding method will be described in detail below.

2-1) Layer configuration of the pressure roller 24 The pressure roller 24 of the present invention has at least the outer periphery of the core metal 24a,
1: Elastic layer 24c made of a flexible and heat resistant material typified by silicone rubber.
2: A release layer 24e having a high release performance represented by a fluororesin.
3: Adhesive layer 24d for adhering elastic layer 24c and release layer 24e, which contains a monomer electrolyte in a silicone rubber adhesive.
Is a pressure roller in which are stacked. The following layers may be added as necessary.
4: Adhesive layer 24b for adhering the cored bar 24a and the elastic layer 24c.
In addition, there is no problem with multiple layers as long as the function of the present case is not impaired.

2-1-1) Core 24a
An iron or aluminum mandrel is preferably used, and after activating the surface with sandblast or the like in advance, it may be degreased with methylene chloride, a hydrocarbon-based detergent or an aqueous detergent.

2-1-2) Adhesive layer 24b
By using a primer for peroxide vulcanization type silicone rubber or a primer for addition type silicone rubber, the cored bar 24a and the elastic layer 24c can be firmly bonded. If necessary, it may be fired at 120 ° C. to 170 ° C. for about 30 minutes to 1 hour.

2-1-3) Elastic layer 24c
The elastic layer 24c is a layer for forming the fixing nip portion N as described above, and may be a solid rubber elastic layer or a foamed rubber layer. The thickness of the elastic layer 24c used for the pressure roller 24 is not particularly limited as long as it can form the fixing nip portion N having a desired width, but is preferably 2 to 10 mm.

  Any of the following may be suitably used as the main polymer of the elastic layer 24c. For example, high temperature vulcanization type silicone rubber (HTV), addition reaction curable type silicone rubber (LTV), condensation reaction curable type silicone rubber (RTV), fluorine rubber, or a mixture thereof can be used. Specifically, for example, silicone rubber such as dimethyl silicone rubber, fluorosilicone rubber, methylphenyl silicone rubber, vinyl silicone rubber; vinylidene fluoride rubber, tetrafluoroethylene-propylene rubber, tetrafluoroethylene-perfluoromethyl vinyl ether rubber, Fluorophore such as phosphazene-based fluororubber and fluoropolyether can be used. These main polymers can be used alone or in combination of two or more. Carbon black and reinforcing fillers such as wet silica and dry silica, and fillers such as calcium carbonate and quartz powder may be added to the main polymer.

Moreover, in order to provide conductivity, the volume resistivity value may be lowered by using various conductivity imparting agents as fillers. Examples of these conductivity-imparting agents include conductive carbon blacks such as acetylene black and ketjen black, metal powders such as graphite, silver, copper, and nickel, conductive zinc white, conductive calcium carbonate, and carbon fibers. Carbon black is common.
When the elastic layer 24c is a foam layer, a hollow spherical filler such as a glass balloon or a silica balloon may be dispersed in the main polymer described above.
A predetermined amount of a desired filler is blended and dispersed in the main polymer, and a coating is formed on the adhesive layer 24b on the core metal 24a by a known method such as a die casting method or a ring coating method, and is removed after heat curing. Just type.

2-1-4) Adhesive layer 24d
The adhesive layer 24d provided in the pressure roller is characterized in that it exhibits better charging performance than conventional electronic conductive additives. As the main material used for the adhesive layer 24d, a silicone rubber adhesive type is suitable in terms of heat resistance, adhesiveness, and processability, and the adhesive layer 24d contains a monomer electrolyte in the silicone rubber adhesive. As the silicone rubber adhesive type, it is possible to firmly bond the elastic layer 24c and the release layer 24e by using the following materials. Type A: A commercially available addition-type silicone rubber adhesive.
Type B: A composition obtained by blending an adhesion imparting agent with an addition-type silicone rubber composition not blended with an adhesion imparting agent.

By mixing a monomer electrolyte described below with a solvent diluted with a solvent, both type A and type B can be used as the adhesive layer 24d of the present invention.
The thickness of the adhesive layer 24d is preferably 1 μm or more and 40 μm or less. It is difficult to make the coating thinner than 1 μm, and if it exceeds 40 μm, the function of the elastic layer as a pressure roller is affected. For example, the effect of imparting low thermal conductivity (heat insulation) or high thermal conductivity to the elastic layer may be reduced by increasing the thickness of the adhesive layer.
In addition, the adhesion-imparting agent for the adhesive layer 24d rarely reacts with the main polymer of the elastic layer 24c to increase the hardness of the elastic layer. Although this phenomenon depends on the type of the main polymer, the reaction amount of the adhesion-imparting agent increases as the thickness of the adhesive layer 24d increases. Therefore, the thickness of the adhesive layer 24d is 40 μm or less from the viewpoint of elastic layer hardness change. preferable.
As the monomer electrolyte contained in the silicone rubber adhesive, a fluorine-based surfactant is preferable from the viewpoint of high heat resistance. Among the fluorosurfactants, the following substances selected from sulfonic acids, disulfonic acids, sulfonimides and sulfonamides of fluoroalkylsulfonic acid derivatives are preferably used.

  For example, as sulfonic acid, lithium trifluoromethanesulfonate, potassium trifluoromethanesulfonate, sodium trifluoromethanesulfonate, ammonium trifluoromethanesulfonate, potassium pentafluoroethanesulfonate, lithium pentafluoroethanesulfonate, sodium pentafluoroethanesulfonate , Ammonium pentafluoroethanesulfonate, potassium heptafluoropropanesulfonate, lithium heptafluoropropanesulfonate, sodium heptafluoropropanesulfonate, ammonium heptafluoropropanesulfonate, potassium nonafluorobutanesulfonate, lithium nonafluorobutanesulfonate, Sodium nonafluorobutanesulfonate, nonafluorobutanesulfone Ammonium, potassium perfluorobutane sulfonate, and the like perfluoro lithium butane sulfonic acid.

  As the disulfonic acid, 1,1,2,2,3,3-hexafluoropropane-1,3-disulfonic acid, 1,1,2,2,3,3-hexafluoropropane-1,3-disulfonic acid Dipotassium salt, 1,1,2,2,3,3-hexafluoropropane-1,3-disulfonic acid disodium salt, 1,1,2,2,3,3-hexafluoropropane-1,3- Examples thereof include disulfonic acid diammonium salt and 1,1,2,2,3,3-hexafluoropropane-1,3-disulfonic acid dilithium salt.

  Sulfonimides include bis (heptafluoropropanesulfonyl) imide potassium salt, bis (heptafluoropropanesulfonyl) imide lithium salt, bis (heptafluoropropanesulfonyl) imide sodium salt, bis (heptafluoropropanesulfonyl) imide ammonium salt, bis ( Nonafluorobutanesulfonyl) imide potassium salt, bis (nonafluorobutanesulfonyl) imide sodium salt, bis (nonafluorobutanesulfonyl) imide ammonium salt, bis (nonafluorobutanesulfonyl) imide lithium salt, cyclo-hexafluoropropane-1, 3-bis (sulfonyl) imide potassium salt, cyclo-hexafluoropropane-1,3-bis (sulfonyl) imide sodium salt, cyclo-hexafluoropropane 1,3-bis (sulfonyl) imide ammonium salt, cyclo - hexafluoropropane-1,3-bis (sulfonyl) imide lithium salt and the like.

Examples of the sulfonamide include trifluoromethanesulfonamide potassium salt, pentafluoroethanesulfonamide, pentafluoroethanesulfonamide potassium salt, heptafluoropropanesulfonamide, heptafluoropropanesulfonamide potassium salt, and nonafluorobutanesulfonamide potassium salt. .
Since the fluoroalkylsulfonic acid derivative has a very high decomposition temperature and high ionic conductivity, it is suitable for inclusion in silicone rubber. The addition amount of the fluoroalkylsulfonic acid derivative to the silicone rubber is preferably 0.005 part or more and 3 parts or less with respect to 100 parts of the silicone rubber. Here, the amount added is only the amount of the raw material not including the amount of the solvent. If it is 0.005 part or less, the effect of suppressing charging is insufficient, and if it is more than 3 parts, the adhesiveness deteriorates.
In order to contain the monomer electrolyte in the silicone rubber adhesive, a solution obtained by mixing the monomer electrolyte in an organic solvent may be mixed with the silicone rubber. The silicone rubber adhesive may be used in combination with various conductivity imparting agents as a filler.

2-1-5) Release layer 24e
As the release layer 24e, for example, a fluororesin exemplified below in a tube shape or a paint is used.

Homopolymers such as polyvinylidene fluoride and polyvinyl fluoride, binary copolymers of ethylene and tetrafluoroethylene (hereinafter abbreviated as ETFE), binary copolymers of ethylene and trifluoroethylene chloride, And a binary copolymer of ethylene fluoride and perfluoroalkyl vinyl ether (hereinafter abbreviated as PFA), and a binary copolymer of tetrafluoroethylene and hexafluoropolypropylene. Of these, PFA and ETFE are more preferable from the viewpoints of moldability, heat resistance, and bending resistance.
The type is preferably a tube from the viewpoint of strength and workability. The thickness of the release layer 24e is preferably 100 μm or less. This is because the elasticity of the lower elastic layer 24c can be maintained when the layers are stacked, and the surface hardness of the pressure member can be prevented from becoming too high.
The inner surface of the release layer 24e can be improved in adhesion by performing sodium treatment, excimer laser treatment, ammonia treatment or the like in advance. As a method for coating the release layer 24e, a method of coating the adhesive layer 24d as a lubricant after removing the roller from the mold can be used. The release layer 24e may be formed by coating a material obtained by coating the material.
The adhesive layer 24d included in the pressure roller 24 is characterized by high charge suppression performance. In addition, by reducing the resistance of the elastic layer 24c of the pressure roller 24, further excellent charge attenuation performance is achieved. The pressure roller 24 can be provided.

Moreover, the effect which suppresses electrostatic offset can further be heightened by applying a voltage to the pressure roller 24 by a voltage application means. The voltage applying means may be provided on the heating member or on both.
Here, even in a system other than the film heating system as in this example, for example, a heat roller system, the same effect can be obtained by adopting a configuration having the pressure roller described below and the voltage applying means.

  Hereinafter, the present invention will be described more specifically with reference to examples.

Example 1
First, a primer for addition curing silicone rubber (trade name: DY39-051 A &B; “A liquid” manufactured by Toray Dow Corning Co., Ltd.) and “ Equivalent amount of “Liquid B” was sprayed and fired at 150 ° C. for 30 minutes.

Next, an addition curing type liquid conductive silicone rubber material DY35-1349SC A & B manufactured by Toray Dow Corning Co., Ltd. (volume resistance value is 10 ⁶ Ω · cm product) 50 parts each of liquid A (main agent) / liquid B (curing agent), and after first vulcanizing at 150 ° C. for 1 hour, the mold is removed from the mold to form elastic layer 24c. Obtained. (Hereinafter referred to as roll-shaped product A)
Next, as an adhesive layer 24d, an addition-curable silicone rubber adhesive (trade name: SE1819CV; "Part A" and "Part B" manufactured by Toray Dow Corning Co., Ltd., equal parts 100 parts) potassium pentafluoroethanesulfonate (C2F5SO3K) 0.5 part was added, and it apply | coated uniformly with the thickness of 5 micrometers on the roll-shaped molded object A. As shown in FIG. (Hereinafter referred to as roll-shaped molded product B)
The release layer 24e was formed into a tube shape having a thickness of 50 μm, and PFA (trade name: 451HP-J) manufactured by DuPont was used.
The fluororesin tube as the release layer 24e described above is coated on the roll-shaped molded product B, heat-cured at 200 ° C. for 4 hours, and then the excess end portion is cut to apply the pressurization of this embodiment. A roller 24 was obtained.
The fixing belt 23 is made of a SUS material having an outer diameter of Φ30 and a thickness of 30 μm as a base layer, a silicone rubber elastic layer to which an alumina filler is added on the base layer, 250 μm, and a PFA having a thickness of 15 μm as a release layer on the silicone rubber elastic layer. The coated one was used.
The base layer of the fixing belt 23 was grounded, and a plus 600 V voltage was applied to the core of the pressure roller.

(Electrostatic offset evaluation)
The electrostatic offset was evaluated by the following method. The fixing device of this example was incorporated into HP-Laser Jet P4515 (A4 60 sheets / min) which is an LBP (laser beam printer), and Neenah Bond 60 g / m2 paper manufactured by Neenah Paper was used in a low temperature and low humidity environment (15 ° C / 50% of the halftone image pattern was continuously passed through the paper left at 10%, and the electrostatic offset was evaluated. The toner used in this evaluation is evaluated using a negative toner having a characteristic of being charged to a negative polarity.

Evaluation was classified as follows.
○: Not generated at all.
Δ: Rarely occurs partially.
X: A ugly offset occurs.

(Potential measurement)
During the electrostatic offset evaluation, the surface potential Vp of the pressure roller 24 and the surface potential Vb of the fixing belt 23 were measured with a surface potential meter (Model 344) manufactured by TREK JAPAN.
The offset potential was determined as a potential difference Vo = Vp−Vb. Since the potential difference Vo is positive, and the larger the value is, the stronger the force of attracting the toner onto the recording material P is. Therefore, the potential difference Vo is effective for electrostatic offset and can be determined to be almost equal to the image level. For convenience, the above three types are classified, but it can be determined that the larger the potential difference Vo is, the more effective the electrostatic offset is.

(Toner stains)
Toner stains were evaluated using 75 g / m 2 (trade name: X-9) manufactured by Boise Cascade with calcium carbonate as a filler. Using the above-mentioned LBP and the fixing device of this embodiment, 5000 sheets were passed in a print mode in which the sheet was allowed to stand for 10 minutes after passing 2 sheets in a low-temperature and low-humidity environment (15 ° C./10%) to evaluate pressure roller contamination. They were classified as follows.
A: Not generated at all.
○: Slight dirt is generated on the pressure roller, but it does not adhere to the paper.
X: The pressure roller is ugly and dirty and adheres to the paper.

(Examples 2 and 3)
Example 1 is the same as Example 1 except that the formulation of potassium pentafluoroethanesulfonate (C2F5SO3K) with respect to 100 parts of the addition-curable silicone rubber adhesive of the adhesive layer 24d is changed as described in Table 1.

Example 4
Example 1 is the same as Example 1 except that 0.5 part of lithium trifluoromethanesulfonate (CF3SO3Li) is used with respect to 100 parts of the addition-curable silicone rubber adhesive of the adhesive layer 24d.

(Example 5)
0.5 parts of 1,1,2,2,3,3-hexafluoropropane-1,3-disulfonic acid dipotassium salt (KO3SCF2CF2CF2SO3K) is added to 100 parts of the addition-curable silicone rubber adhesive of the adhesive layer 24d. It is the same as that of Example 1 except having used what was contained.

(Example 6)
Example 1 except that 0.5 part of bis (heptafluoropropanesulfonyl) imide potassium salt ((C3F7SO2) 2NK) was used for 100 parts of the addition-curable silicone rubber adhesive of the adhesive layer 24d. The same shall apply.

(Example 7)
Example 1 is the same as Example 1 except that 0.5 part of trifluoromethanesulfonamide potassium salt (CF3SO2NHK) is used with respect to 100 parts of the addition-curable silicone rubber adhesive of the adhesive layer 24d.

(Examples 8 and 9)
Example 1 is the same as Example 1 except that the thickness of the adhesive layer 24d is changed as described in Table 1.

(Example 10)
Example 1 is the same as Example 1 except that the core metal is grounded without applying a voltage to the pressure roller.

(Example 11)
As shown in FIG. 2, two voltage application circuits (25, 26) are provided in the fixing device 6, one applies a voltage of minus 400 V to the base layer of the fixing belt 23, and the other applies the same as in the first embodiment. The configuration is such that plus 600 V is applied to the cored bar 24 a of the pressure roller 24. The pressure roller 24 is the same as in the first embodiment.

(Comparative Example 1)
Example 1 is the same as Example 1 except that the formulation of potassium pentafluoroethanesulfonate (C2F5SO3K) with respect to 100 parts of the addition-curable silicone rubber adhesive of the adhesive layer 24d is changed as described in Table 1.

(Comparative Example 2)
As the adhesive layer 24d, only an addition curing type silicone rubber adhesive (trade name: SE1819CV; 100 parts of “A liquid” and “B liquid” manufactured by Toray Dow Corning Co., Ltd.) is used. Both rollers were grounded without applying voltage.

(Comparative Example 3)
It is the same as Comparative Example 2 except that a plus 600 V is applied to the core of the pressure roller 24.

(Comparative Example 4)
As an adhesive layer 24d, an addition curing type silicone rubber adhesive (trade name: SE1819CV; 100 parts of “A liquid” and “B liquid” manufactured by Toray Dow Corning Co., Ltd.) is mixed into Ketjen Black as a conductive carbon black. The same as Example 1 except that 3 parts of EC600-JD (trade name, manufactured by Lion) were added.

(Comparative Example 5)
The configuration is the same as that of Comparative Example 2 except that the fluororesin tube of the release layer 24e is composed only of DuPont's low resistance PFA (trade name: C-9068).

  Table 1 summarizes the evaluation of the above examples and comparative examples.

Here, in the configurations of Comparative Example 1 to Comparative Example 3, the pressure roller contamination was good, but severe electrostatic offset occurred. This is due to the fact that the release layer 24e of the pressure roller 24 cannot be negatively charged.
Regarding Comparative Example 1, the potential difference Vo was improved compared to Comparative Examples 2 and 3, but a large effect was not obtained because the amount of the monomer electrolyte added was small.
Further, when Ketjen Black is included in the adhesive layer 24d as in Comparative Example 4, although there is an effect of suppressing electrostatic offset from Comparative Example 1 to Comparative Example 3, it is extremely rarely partially electrostatic. An offset has occurred.
In addition, when a low resistance PFA tube was used for the release layer 24e as in Comparative Example 5, an electrostatic offset did not occur at all, and the pressure roller was smeared, and the toner adhered to the paper.

In any of Examples 1 to 11, good results were obtained for both electrostatic offset and pressure roller contamination. Further, the potential difference between the fixing belt 23 and the pressure roller 24 is also positive, and it can be seen that the electrostatic offset is good from the viewpoint of potential.
From Example 2, Example 3, and Comparative Example 1, it can be seen that 0.005 part or more of potassium pentafluoroethanesulfonate (C2F5SO3K) is required.
From Examples 1 and 4, lithium trifluoromethanesulfonate (CF3SO3Li) was also as effective as potassium trifluoromethanesulfonate (C2F5SO3K).
From Example 5 to Example 7, good results were obtained with disulfonic acid, sulfonimide and sulfonamide as well as sulfonic acid.
From Example 8 and Example 9, good results were obtained when the thickness of the adhesive layer 24d was in the range of 1 to 40 μm.
From Example 10 and Comparative Example 2, it can be seen that the configuration of the present invention is effective in electrostatic offset even in the configuration in which no voltage is applied to the pressure roller 24.
From Example 11, it was possible to eliminate the pressure roller contamination by applying a voltage to both the fixing belt 23 and the pressure roller 24 to increase the potential difference Vo. It has also been found that a voltage in a direction to press the image on the recording material against the recording material may be applied to at least one of the heating member and the pressure roller.
The voltage value applied to the fixing belt 23 and the pressure roller 24 is not limited to this embodiment, and may be set as appropriate so as to increase the potential difference Vo between the fixing belt 23 and the pressure roller 24.

6 Fixing device 22 Heater 23 Fixing belt 24 Pressure roller 25, 26 Voltage application means

Claims (11)

A pressure roller for forming a nip portion for heating while sandwiching and conveying a recording material carrying an image together with a heating member, comprising at least a core metal, an elastic layer, a release layer, the elastic layer, and the In a pressure roller having an adhesive layer for adhering a release layer,
The adhesive layer contains a monomer electrolyte ;
The pressure roller, wherein the monomer electrolyte is a fluorine-based surfactant .   The pressure roller according to claim 1, wherein the fluorosurfactant is a fluoroalkylsulfonic acid derivative.   The pressure roller according to claim 2, wherein the fluoroalkylsulfonic acid derivative contains any one of sulfonic acid, disulfonic acid, sulfonimide, and sulfonamide.   The pressure roller according to claim 1, wherein the adhesive layer has a thickness of 1 μm or more and 40 μm or less. In a fixing device comprising: a heating member; and a pressure roller that forms a nip portion for heating while sandwiching and conveying a recording material carrying an image together with the heating member.
The fixing device according to claim 1, wherein the pressure roller is the pressure roller according to claim 1.   The fixing device according to claim 5, further comprising: a voltage applying unit configured to apply a voltage in a direction in which an image on the recording material is pressed against the recording material to at least one of the heating member and the pressure roller. A pressure roller for forming a nip portion for heating while sandwiching and conveying a recording material carrying an image together with a heating member, comprising at least a core metal, an elastic layer, a release layer, the elastic layer, and the In a pressure roller having an adhesive layer for adhering a release layer,
The pressure roller, wherein the adhesive layer is formed of silicone rubber having an adhesive component and contains a monomer electrolyte.   The pressure roller according to claim 7, wherein the content of the monomer electrolyte with respect to 100 parts of the silicone rubber is 0.005 part or more and 3 parts or less.   The pressure roller according to claim 7 or 8, wherein the monomer electrolyte is a fluorine-based surfactant.   The pressure roller according to claim 9, wherein the fluorosurfactant is a fluoroalkylsulfonic acid derivative.   The pressure roller according to claim 10, wherein the fluoroalkylsulfonic acid derivative contains any one of sulfonic acid, disulfonic acid, sulfonimide, and sulfonamide.

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